1. Field of the Invention
This invention relates to ski bindings. More particularly, the invention relates to ski bindings which are adapted to be used for cross-country/telemark skiing.
2. State of the Art
Cross-country and telemark skiing are both performed with the heel of the boot free to rotate upward and forward during the skiers stride. Present bindings retain the toe of the boot sole in a rigid or semi-rigid position, and rely upon boot sole flexure to permit the boot to rotate about the toe. Alternately, the binding and the toe of the sole may rotate together.
The resurgence of telemark skiing over the past ten years has spurred an intensive developmental race for technological advancement to telemark ski equipment. In the late 1970's when "cross-country" skiers began telemark skiing at lift serviced areas, new demands were made of the cross-country ski equipment available at the time. Numerous changes were made in the boot design to make it more like that of an alpine boot including a stiffer sole and thicker leather for better torsional control and a higher, stiffer cuff. This was the birth of a new sport: telemark skiing.
Over the past ten years, many skiers have turned to telemark skiing as an alternative to alpine skiing and in so doing have made new demands on their equipment. The ski industry responded by beefing up telemark boots and bindings to support a more aggressive manner of skiing. The three-pin or traditional cable binding system, originally intended to be used in cross country skiing was restructured for telemark skiing. This restructuring included placing stiff plastic cuffs and a stiffer sole in the boots and using stronger materials for the binding in an attempt to make the telemark boot and binding system withstand the demands traditionally met by alpine skiing equipment.
There are several obvious advantages to using a telemark system which explain its recent rise in popularity in both the U.S. and Europe: (1.) Telemark equipment is very light weight, (2.) it provides for a very efficient means of mobility utilizing its flexible toe, and (3.) it performs well in skiing downhill in the free heel position through powder snow. However the use of the conventional telemark system when skiing at lift serviced resort areas, put a greater strain on the bindings and skiers legs and thus causes concern for the safety of the skier in terms of injury. Safety release bindings are becoming necessary to combat the possibility of injury in the sport of telemark skiing as flexible soled boots and binding become more rigid.
Another sport known as ski touring has also become popular over the past ten years. The object is to ski cross country (tour) to a remote destination high up in the mountains and ski downhill through uncut powder snow on possibly new and more challenging terrain in a setting away from the crowds and tracked snow conditions of the lift serviced ski area. The equipment used is either a traditional telemark boot-binding setup or what is referred to as alpine touring binding-boot setup. Alpine touring bindings consist of a plate that is hinged at the toe end of the binding with the heel free to allow for the mobility of a cross-country system while in touring mode. For the ski descent, a downhill or alpine style technique is desired and the heel end of the binding is releasably locked down. The heel lock down is made releasable to avoid skier injury.
For the telemark skier, the simple three-pin and common cable bindings in use today are still held as the best system available when the advantage of having a flexible toed boot is desired for cross-country travel and telemark skiing. However the problem with the three-pin system is that it is torsionally unresponsive to the skier, i.e., it has a certain amount of twist in the sole of the boot which makes it difficult to hold an edge on packed powder or icy slopes. The ski industry has made the boots stronger, higher, and more rigid with plastic inserts and improved structural characteristics, but the structural rigidity had not been improved appreciably until recently.
Finally, a full plastic telemark boot has been developed which has increased the stability and overall torsional rigidity of the boot. Because of this inherent stiffness of the toe of the boot it has become necessary to use a telemark cable binding system instead of the three pin binding in order to force the boot to flex at the desirable location required to perform stable telemark turns.
The improved performance of the new plastic telemark boots has brought about an urgent need for a releasable binding system which utilizes the advantages of the cable binding system. By combining a conventional release system with a conventional cable binding system the weight of the two become a considerable drawback. The weight of the conventional cable binding system is due to the heavy steel springs and cable tightening latch. These steel springs are necessary to allow the cable to be effectively lengthened or extended through the stretch in the spring but are not critical to the binding in so far as providing for a reliable high performance release The weight associated with releasable system is due to the release springs and the bulk of the heel clamping means for the anterior (forward) release system completely independent of the cable system. Combining the weights of the two systems takes away the weight advantage of using the type of free-heel systems enjoyed by the telemark skier today.
The cable systems currently on the market are some what heavy compared to the three pin binding but provide for an overall greater amount of control by biasing the ball of the foot to the ski. This downward biasing of the toe has become a necessity in using the new stiff plastic boot. The combined weight of the plastic boot and conventional cable binding makes it considerable heavier and therefor less desirable for back country or non-lift serviced area touring.
The binding of the present invention eliminates the need for these springs by providing a much lighter and effective cable extension means and cable tightening means. It is able to reduce the weight of the cable system of the invention by nearly 1/2 as compared to conventional cable bindings available. It also incorporates a anterior safety release system without adding any additional weight to the cable system by utilizing the cable extension mechanism. This weight reduction not only makes the new design lighter overall as compared to the telemark cable binding but provides for the same safety feature and ability to lock the heel of the boot down for an alpine descent as found in alpine touring binding systems at a small fraction of the weight.